Control of electric motors.



H. A. MAYOR.

CONTROL OF ELECTRIC MOTORS.

APPLICATION TILED SEPT. 4, 1909.

Patented Dec.28,1909.

UNITED HENRY ALEXANDER I CON fii iA-SS.

To all li i bO'mit may concern:

Be it Known that l, Huxny Sin HARDER Mivon, a StlbjCCi? of the King of Great Brit tin and Ireland, residing at Mile End, in I the cit; and county of Glasgow, Scotland, have invented improvements llielathg to the Control of Electric Motors, of which the t'ollmving is a specification.

This invention relates to the control of electric motors and more especially to those of la rgo power which require to be started, stopped and reversed, it may be While connected to the WOLk which subjects them to full load, and it has for its object to nrovide simple and improved means wherein. it is nsured that prior to operating the controlling switches in any operation which involves interrupting the main circuit the motor with a View to effecting achange of speed or other running condition, the current supplied to the motor is reduced in value orstopped by manipulation of the primary or generator element of the supply circuit and the reduction or stoppage so produced remains until. the desired change has been made in the controlling arrangements in the main circuits of the i'uotors and these circuits are again closed, after which the current 1s restored to the value required for dealing with the Work. i

The invention is particularly applicable Ytor use in marine propulsion embodying self-contained generator and motor the motor or motors being conveniently of the multiphase alternating current type capable or speed regulation in the manner described in the specification of Letters Patent No. 912,14t4r. and the generator driven by a prime mover so that either current of single periodicity is supplied or current of any of number of ditterent periodicities.

The invention, While capable of being varionsly carried into effect, may with advantage be embodied in a plant Where the current is supplied by a turbo-alternator to a motor of the kind ret'erred to in the said former specification No. 912144l. iiccording thereto, it is arranged to vary the excitation of the generator in a gradual manner by a controller, conveniently in the form of arheostat, driven by an auxiliary motor from a suitable source and adapted, it desired, to completely interrupt the circuit of the excitation windings after the insertion of sufiicient resistance therein. This will have the effect of reducing or interru 'ing by a second auxiliary motor the which controlled by means the controlling means of ed for varying the genera or example, the two an ilv may be electrically connected to two-Way switch with circuit hr so nged hen it is required to operswitch or switches controlr or motors, the QIIClL 1g rater or generators red before the revers- -c moved into the open hen. contacts 0 motor oper 1 Q 1 a men, an he excitation the mote operated controller iielc cir uit.

J g dia rammatt es installati n suitable ion with the aid of taree 1* gle electLic generator:

wn, a: is a t'rbine, a the field base alternator drive by to the alternator and ich the motors c con-- the turbine, c d tie circuit to of contacts, of which reversing switch ing current to the 1 rotor While con acts 'nafter termed half speed, and :nce the motor in either c direction, increr ses or aracteristic speed, proer-ein ter' respectively termed duce What is h full speed slou speed.

h is a local circuit supplied with from any suitaf? is source under the of a swit j is a current c ,ntrol t'e r'citer tor the field ato'r having its field 7' connected to resistance in with r operate a series of connected contacts, one of which is herein specifically referred to as the contact m, and a disconnected contact n, adapted to be successively engaged by an arm 0; operated, as by a worm p and worm wheel 32 from an electric motor q. In connection with each motor 6 is a circuit breaker comprising apair of contacts 1, a pair'ot contacts 8 and a pair of contacts If, it' being a bridging member controlled by an electromagnet 24 for bridging either the contacts 1' alone, or the contacts 8 and 2, conjointly.

The circuit oi? each electro magnet u is adapted to be completed across the leads 7i and interrupted by means of a manually operated switch arm a and a series of contacts 11, 12, 13, l t, 15,16 and 17 that are respectively connected to corresponding contacts ll to 17 of a companion switch the arm '0 of which'is arranged to be moved by a motor w, as through. worm w and worm wheel w as hereinafter set forth, the said motor to serving also to operate, as through a worm 7,0 the movable contacts pertaining to the contacts 1 to 10 of the controlling switches of the corresponding motor a.

The movable contacts referred to, which may be of any suitable kind, are only conventionally represented by bars 22 00 w movable with a shaft is. The circuit of the anotor Q is adapted to be completed by brushes, not shown, carried in an insulated manner i'rorn the'switch arm 0 of the eXciter rheostat, firstly through segmental. contacts 3 3 and circuit breaker contacts s, and sec- I ondly through segmental contacts .2 a and the circuit breaker contacts '1', which latter contacts pertaining to all three circuit breakers are arranged in series relationship, necessitating the circuit breakerscbeing in similar positions before the circuit can be completed. The circuits of the motors w are completed through a segmental contact gfi, the segmental contact 3 and the circuit breaker contacts t and s only when the en'- cuit of the motor 9 is interrupted The action is as follows :-Supposing all the elements to be at rest and the order stand by engines be given, then the duty will be to make certain that the manual switch arms a are in engagement with the contacts 11 as shown, corresponding to 0d position, to close the switch 2' of the local circuit h and to start the turbine a.

The closing of the switch 2' will cause current to flow from one lead of the circuit h in parallel through the switch arms o contacts 11 and 11, switch arms a and electromagnets u to the other lead of the circuit h. The

magnets 10 being thereby energized cause the bridging members a of the circuit breakers to move and bridge the contacts 1', whereupon the arrangement is in condition to respond to the order next given. Thus, assuming it is desired to effect propulsion at slow speed ahead, the manual switch arms a would in this particular case be moved into engagement with contacts 12, thereby interrupting the circuit of the electromagnets u and causing the bridging members u? of the circuit breakers to move and bridge the cont cts and t. T he result of this will be to com lete the circuit of the motor Q from. one load of the circuit 12. by way of the segmental contact y, the corresponding insulated brush upon the switch arm -0, segmental contact- 3 and circuit breaker contactsusto the other lead of the circuit h. The motor 9 thereupon starts and movesthe arm 0 in a clockwise direction from-contact m over the "remainder of the series to successively include sections of the resistance Z: in series with the field winding 7' of the exciter j until the contact n is reached when the exciter field circuit is interrupted. As soon as the arm 0 engages the contact a it leaves the segmental contact g and the insulated brush pertaining thereto engages the contact 3, thereby interrupting the circuit of the motor Q. At the same time as the circuits of the exciter field 7' and motor q are interruoted, the circuits of motors are completed in parallel from one load of the circuit h by way of the circuit breaker contacts 1, contact 3 insulated brush on the switch arm 0, segmentatcontact 3 and circuit breaker contacts 8 to the other lead of the circuit h. The motors to then commence to rotate the switch arms '2) in a counter clockwise direction until each contact 12 is engaged whereupon the circuits of the electromagnets u are completed and the circuit breakers restored to positions which interrupt the circuits of the motors w and bridge the contacts 1" in series. The other insulated brush on the switch arm 0 being in engagement with the segmental contacts 2 and 2 the circuit of the motor 9 will be completed from one lead of the circuit h by way of the said contacts 2 2, their co-acting insulated brush, and the contacts 1 oi all the circuit breakers to the otherlead of the circuit h, thereby causing the arm 0 to. continue to move in a clockwise direction and cut out the resistance 7; in the exciter field circuit until the contact m is reached as shown when the circuit of the motor 9 is again interrupted and the parts left in' readiness to re spond to the next order given.

During the movement of each. switch arm 0 from contact 11 to contact 12 as explained above, the motors to have operated the circuit controlling switches of the motors 0 so that contacts 1, 2 may be assumed to be bridged by bar 00 contacts 3 and 6 by bar and contacts 7 and 10 by bar .1 the spinner being in consequence negatively rotated. It will be understood that a similar sequence of steps takes place, whichever contact 11 -to 17,.the switch arm a" is move into engagement with, the only variation consisting l (Hf lZO controlling switches ofthe motors e which may beibriefiy alluded to. Thus contact 13 is intended to produce half speed ahead f in which case bar a) will be assumed to engage contact 1 alone, barai' contact 3 alone and bar .r the contact 7 alone, the spinner thereby being inactive. Contact let is intended to produce full speed ahead in which case bar or will be assumed to bridge contacts 1 and 2, bars in contacts 3 and l and bar a contacts! and 8, the spinner thereby being positively rotated. Contact 15 is intended ,to produce slow speed astern", in which case bar of will be assumed to bridge contacts 1 and 2, ear 3? contacts 4: and 5 and bar 53 contacts and 9, the circuit relationships being relatively the same as for slow speed ahead but reversed. Contact 16 is intended to produce half speed astern in which case bar 11 will be assumed to engage contact 1 alone,

bar a1 contact 5 alone and bar contact 9 alone the spinner being again idle; Finally contact 1 is intended to produce full astern in which case it will be assumed that bar as bridges contacts 1 and 2, bar m contacts 5 and 6 and bar .2? contacts 9 and 10.

-What I claim is 1. Electric motor controlling means, comprising, in combination with a generator and a motor, an exciter, a controller for the exciter, a controller for the motor, auxiliary motors for driving such controllers and interlocking means to insure that one such auxiliary motor can alone be in operation at a time.

2. Electric motor controlling means, comprising, in combination with a generator and a motor, an excite-r for the generator, a field winding for the exciter," a resistance in connection with the field winding and means for altering the active length oi sucl'i resistance, a controller for the motor, an auxiliary motor for operating the resistance varying means, an auxiliary motor operating the motor controller and a switch arrangement adapted to set the motor of the cxciter field resistance varying means in action to alter the generator excitation before the auxiliary motor of the motor controller is set in action.

3. Electric motor controlling means, comprising: in combination with a generator and a motor, an exciter tor the generator, a field winding for the excitor, a resistance in connectionwith the field winding and means for altering the active length of such resistance, an auxiliary motor for operating the resistance varying means, an auxiliary motor for operating the motor controller, and a switch and circuit breaker so that the an Liliary motor of the resistance arrangement electrically connecting the auxiliary motors.

3 first na being re-started to restore the original gensource of electric energy common to hot tirely completing the electric circuit of b achapted to actuate the circuit breaker varying means is set in action to prot generator variation before the other at iary motor can be set in action to move the motor controller to open position and the ied auxiliary motor prevented from erator conditions before the auxiliary motor of the motor controller has moved the motor 1 controller to closed position and stopped.

Electric motor controlling means, comprising, in combination with a generator and a motor, an txcitcr for "the generator motor operated controller for the one motor operated controller for the motor controllers, a circuit breaker for alterin- :1 controller motors and switch operated in one Cl'ilECllOll manually and in the same rection by the motor oi the motor control bring the controller motors into use alien nately',

5. Electric motor controlling means, comprising, in combination with a generator and a motor, an errciter for the generator, a are operated controller for the enciter, a motor operated controller for the motor, a source of of electric energy common to the motors both controllers, a circuit breaker for al" natively completing the electric circuit both motor controllers, an electromagnet winding for operating the circuit breaker, manually operated switch adapted to cornplete the circuit of the said winding and operate toe circuit breaker to close one point the circuit of the exciter controil motor or to interrupt the circuit of he Sti t winding and operate the circuit er 1 open the previously closed point and to clc the circuits of both controller motors other points, and a switch operated lay motor of the motor controller for r pleting the circuit of the circm. winding.

6. Electric motor controlling ineai'is, com-- prising, in combination with generator and a main motor, an exciter for'the generator, a field winding for such enciter, a resistance in connection 'ith the field winding, a switch for fractionally cutting such resistance into and out of circuit with the excitcr field winding, a motor for operating snch switch, a switch for the main motor, an auxiliary motor operating such I swi i, means for starting the motor of the exciter switch while there is no resistance in circuit with the cxciter licld winding to gradually out such resistance into circuit, means tor arresting the excitcr switch motor when all the resistance cut in, means for then auto matically starting the auxiliary motor oil? main motor switch and means operated a 0 03?; C l

Cit

the exciter switch to cut out resistance in the I tors in'operation to alter their running eonex'citer field winding.

7. Electric motor controlling means, coma motor, an exciter for the generator, a motor operated controller for the exciter, a motor operated controller for the motor and means adapted to first set the eXciter controller in operation to decrease the excitation of the generator, then to arrest such controller and set the controller of the motor in operation to alter its running condition and finally to arrest the controller of the motor and restart the eXciter controller to restore the normal excitation .of the generator.

8. Electric motor controlling means, comprising, in combination with a generator and a plurality oi motors, an eXciter for the generator, a motor operated controller for the exciter, a motor operated controller for each motor, means adapted to first set the exciter controller in operation to decrease the excidition and finally to arrest the controllers of the motors and restart the cXciter conprising, in combination With a generator and troller to restore the normal excitation of the generator and means for insuring that the controllers of all the motors shall be in similar positions before such restarting of 5 motor, a source of electric energy common to 4 all the controllers and circuit breakers in- 1 tatlon of the generator, then to arrest such controller and set the controllers of the mo first day 

